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Efficient doping modulation of monolayer WS_2 for optoelectronic applications

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Chinese Physics B 2019年第3期28卷 48-53页

作者： Xinli Ma Rongjie Zhang Chunhua An Sen Wu Xiaodong Hu Jing Liu State Key Laboratory of precision Measurement technology and Instruments School of Precision Instruments and Opto-electronics EngineeringTianjin UniversityTianjin 300072China

Transition metal dichalcogenides(TMDCs) belong to a subgroup of two-dimensional(2 D) materials which usually possess thickness-dependent band structures and semiconducting properties. Therefore, for TMDCs to be widely used in electronic and optoelectronic applications, two critical issues need to be addressed, which are thickness-controllable fabrication and doping modulation of TMDCs. In this work, we successfully obtained monolayer WS2 and achieved its efficient doping by chemical vapor deposition and chemical doping, respectively. The n-and p-type dopings of the monolayer WS2 were achieved by drop coating electron donor and acceptor solutions of triphenylphosphine(PPh3) and gold chloride(AuCl_3), respectively, on the surface, which donates and captures electrons to/from the WS2 surface through charge transfer, respectively. Both doping effects were investigated in terms of the electrical properties of the fabricated field effect transistors. After chemical doping, the calculated mobility and density of electrons/holes are around 74.6/39.5 cm^2 · V^(-1) ·s^(-1)and 1.0 x 10^(12)/4.2 x 10^(11) cm^(-2), respectively. Moreover, we fabricated a lateral WS2 p-n homojunction consisting of nondoped n-type and p-doped p-type regions, which showed great potential for photodetection with a response time of 1.5 s and responsivity of 5.8 A/W at V_G = 0 V and V_D = 1 V under 532 nm light illumination.

关键词： two-dimensional materials tungsten disulfide chemical doping homojunction photodetector

Quantum interference between heralded single photon state and coherent state

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Chinese Physics B 2017年第7期26卷 111-116页

作者：杨磊马晓欣李小英 College of precision Instrument and opto-Electronics Engineering Tianjin UniversityKey Laboratory of Opto-Electronics Information Technology Ministry of Education High School Affiliated to Beijing Institute of technology

Balanced homodyne detection has been introduced as a reliable technique of reconstructing the quantum state of a single photon Fock state, which is based on coupling the single photon state and a strong coherent local oscillator in a beam splitter and detecting the field quadrature at the output ports separately. The main challenge associated with a tomographic characterization of the single photon state is mode matching between the single photon state and the local oscillator. Utilizing the heralded single photon generated by the spontaneous parametric process, the multi-mode theoretical model of quantum interference between the single photon state and the coherent state in the fiber beam splitter is ***, the analytical expressions of the temporal-mode matching coefficient and interference visibility and relationship between the two parameters are shown. In the experimental scheme, the interference visibility under various temporalmode matching coefficients is demonstrated, which is almost accordant with the theoretical value. Our work explores the principle of temporal-mode matching between the single photon state and the coherent photon state, originated from a local oscillator, and could provide guidance for designing the high-performance balanced homodyne detection system.

关键词： heralded single photon state coherent state quantum interference balanced homodyne detection

Global Calibration Method of Multi-sensor Vision System Using Skew Laser Lines

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Chinese Journal of Mechanical Engineering 2012年第2期25卷 405-410页

作者： LIU Qianzhe SUN Junhua LIU Zhen ZHANG Guangjun Key Laboratory of precision opto-mechatronics technology of Ministry of Education Beihang UniversityBeijing 100191China

Multi-sensor vision system plays an important role in the 3D measurement of large ***,due to the widely distribution of sensors,the problem of lacking common fields of view（FOV） arises frequently,which makes the global calibration of the vision system quite *** primary existing solution relies on large-scale surveying equipments,which is ponderous and inconvenient for field *** this paper,a global calibration method of multi-sensor vision system is proposed and *** proposed method utilizes pairs of skew laser lines,which are generated by a group of laser pointers,as the calibration *** pair of skew laser lines provides a unique coordinate system in space which can be reconstructed in certain vision sensor＇s coordinates by using a planar *** the geometries of sensors are computed under rigid transformation constrains by taking coordinates of each skew lines pair as the *** method is applied on both visual cameras with synthetic data and a real two-camera vision system;results show the validity and good *** prime contribution of this paper is taking skew laser lines as the global calibration objects,which makes the method simple and *** method need no expensive equipments and can be used in large-scale calibration.

关键词： multi-vision system global calibration non-overlapping cameras skew laser lines

Effect of optical pump on the dielectric properties of SrTiO_3 in terahertz range

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Chinese Physics B 2014年第3期23卷 316-319页

作者：吴亮蒋霖坤袁偲丁欣姚建铨 College of precision Instrument and opto-electronics Engineering Institute of Laser and Opto-electronics Tianjin University Key Laboratory of opto-electronics Information technology of Ministry of Education Tianjin University

Tuning the dielectric permittivity spectra of strontium titanate （SrTiO3） single crystals in an extemal optical field is investigated at room temperature by means of terahertz time-domain spectroscopy. The application of the optical field leads to an appreciable tuning of the permittivity, reaching up to 2.8%, with the dielectric loss changing about 3%. The observed behavior is interpreted in terms of soft-mode hardening due to the anharmonic character of its potential. We also find that the change of the refractive index responds linearly to the applied light power. These findings are attributed to a linear electro-optical effect of the internal space charge field of the crystal.

关键词： THz materials optical constants ferroelectrics

Multi-Wavelength Conversion Based on Single Wavelength Results in Phase Retardation Measurement

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Chinese Physics Letters 2013年第3期30卷 60-62页

作者： CHEN Wen-Xue ZHANG Shu-Lian LONG Xing-Wu Department of opto-electronic Engineering College of Opto-electronic Science and EngineeringNational University of Defense TechnologyChangsha 410073 The State Key Lab of precision Measurement technology and Instrument Department of Precision InstrumentsTsinghua UniversityBeijing 100084

We introduce an instrument for single wavelength measurement of phase retardation based on the laser feedback phenomenon.A method of multi-wavelength conversion for this instrument is proposed and the conversion results are *** calibration is used to eliminate the conversion *** experimental results show that the maximum error after conversion is 0.26°.Through the present work,the application of laser feedback instrument for single wavelength measurement of a wave plate is expanded to the multi-wavelength *** will expand the application area of the instruments.

关键词： instrument eliminate expanded

Low-loss terahertz waveguide with InAs-graphene-SiC structure

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Chinese Physics B 2014年第5期23卷 323-327页

作者：徐德刚王与烨于红李佳起李忠孝闫超张昊刘鹏翔钟凯王卫鹏姚建铨 College of precision Instrument and opto-electronics Engineering Tianjin University Key Laboratory of opto-electronics Information technology Tianjin UniversityMinistry of Education

We demonstrate a low-loss terahertz waveguide based on the InAs-graphene-SiC structure. By analyzing the terahertz waveguide proposed in this paper, we can obtain that it is the characteristic of a low transmission loss coefficient （αloss 0.55 dB/m） for fundamental mode （LP01） when the incident frequency is larger than 3.0 THz. The critical radii of the inside and outside cylinders have been found for the high-quality transmission. The large inside radius and the high transmission frequency result in a fiat transmission loss coefficient curve. As a strictly two-dimensional material, the double graphene surface rings perform better to improve the quality of transmission mode. These results provide a new idea for the research of the long-distance THz waveguide.

关键词： InAs-graphene-SiC structure low-loss terahertz waveguide transmission critical radii

High-power terahertz radiation from surface-emitted THz-wave parametric oscillator

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Chinese Physics B 2011年第5期20卷 280-284页

作者：李忠洋姚建铨徐德刚钟凯汪静丽邴丕彬 College of precision Instrument and opto-electronics Engineering Institute of Laser and Opto-electronicsTianjin University Key Laboratory of opto-electronics Information Science and technology of Ministry of Education Tianjin University

We report a pulsed surface-emitted THz-wave parametric oscillator based on two MgO：LiNbO3 crystals pumped by a multi-longitudinal mode Q-switched Nd：YAG laser. Through varying the phase matching angle, the tunable THzwave output from 0.79 THz to 2.84 THz is realized. The maximum THz-wave output was 193.2 n J/pulse at 1.84 THz as the pump power density was 212.5 MW/cm2, corresponding to the energy conversion efficiency of 2.42Х10-6 and the photon conversion efficiency of about 0.037%. When the pump power density changed from 123 MW/cm^2 to 148 MW/cm^2 and 164 MW/cm^2, the maximum output of the THz-wave moved to the high frequency band. We give a reasonable explanation for this phenomenon.

关键词： THz-wave parametric oscillator noncollinear phase matching THz-wave polarization,frequency tunable output

Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

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Chinese Physics B 2008年第1期17卷 211-216页

作者：丁欣张少敏马洪梅庞明姚建铨李卓 College of precision Instrument and opto-Electronics Engineering Institute of Laser and Opto-Electronics Tianjin University Key Laboratory of opto-Electronics Information Science and technology Ministry of Education Cooperated Institute of Nankai University and Tianjin University School of Information Science and technology Department of Opto-Electronic EngineeringBeijing Institute of Technology

This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.

关键词： continuous-wave mid-infrared intracavity optical parametric oscillator periodically poled lithium niobate crystal

Controllable blood–brain barrier(BBB)regulation based on gigahertz acoustic streaming

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Nanotechnology and precision Engineering 2022年第4期5卷 1-7页

作者： Hang Qi Shuaihua Zhang Jiaxue Liang Shan He Yanyan Wang State Key Laboratory of precision Measuring technology and Instruments School of Precision Instrument and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China

The blood–brain barrier(BBB)is a structural and functional barrier necessary for brain homeostasis,and it plays an important role in the realization of neural function and in protecting the brain from damage by circulating toxins and ***,the extremely dense BBB also severely limits the transport of molecules across it,which is a great hindrance to the diagnosis and treatment of central nervous system(CNS)*** paper reports a new method for controllable opening of the BBB,based on the gigahertz acoustic streaming(AS)generated by a bulk acoustic wave resonant *** adjusting the input power and working distance of the device,AS with tunable flow rate can be generated to disrupt tight junction proteins(TJs)between endothelial *** results obtained with this method show that the gigahertz AS promotes the penetration of dextran molecules with different molecular weights across the *** work provides a new platform for studying the mechanical regulation of BBB by fluid shear forces and a new method for improving the efficiency of drug delivery.

关键词： Blood–brain barrier Mechanical regulation Drug delivery Bulk acoustic wave Acoustic streaming